JP6844971B2 - Grinding device - Google Patents

Description

The present invention relates to a grinding device that grinds while measuring the thickness of a plate-shaped workpiece.

As a grinding device, a non-contact type thickness measuring device is known to grind while measuring the thickness of a plate-shaped workpiece (see, for example, Patent Document 1). The non-contact type thickness measuring device irradiates the plate-shaped work with measurement light such as infrared laser light, and measures the thickness of the plate-shaped work based on the reflected light from the upper and lower surfaces of the plate-shaped work. Water is supplied from the thickness measuring instrument to the upper surface of the plate-shaped work, and the space between the thickness measuring instrument and the plate-shaped work is sealed with water so that the measurement light is not blocked by the spray (spray) of the grinding water. By irradiating the plate-shaped work with the measurement light through the water layer, the thickness of the plate-shaped work is measured with high accuracy.

Japanese Patent No. 5731806

By the way, some plate-shaped workpieces have a resin layer formed on the surface, and there is a desire to measure the thickness of the resin layer when grinding the resin layer. However, since the refractive index of the resin and water are close to each other, the measurement light is not properly reflected at the interface between the resin layer and the water, and the reflected light from the upper and lower surfaces of the resin layer cannot be received. Further, when the grinding wheel is rotated at a high speed during grinding, the spray of grinding water is likely to be scattered, and when the grinding wheel is rotated at a low speed, the spray of grinding water is unlikely to be scattered. Therefore, it is not necessary to measure the thickness of the plate-shaped work while filling the space between the thickness measuring device and the plate-shaped work with water at the time of low-speed rotation where the influence of spraying is small.

The present invention has been made in view of the above points, and one of the objects of the present invention is to provide a grinding apparatus capable of appropriately measuring the thickness of a plate-shaped workpiece according to the grinding processing conditions.

The grinding apparatus according to one aspect of the present invention includes a holding table for holding a plate-shaped work composed of one layer or two layers of an upper layer and a lower layer, a grinding means for grinding the plate-shaped work held by the holding table with a grinding wheel, and a grinding means. The plate-shaped work ground in the above is irradiated with the measurement light, and the first reflected light reflected on the upper surface of the plate-shaped work and the measurement light passing through the upper surface are reflected at the lower surface of one layer or the interface between the upper layer and the lower layer . the reflected light to a grinding apparatus and a non-contact thickness gauge for measuring the thickness or the upper layer of the thickness of the plate-shaped workpiece from the optical path difference between the first reflected light and second reflected light received, The non-contact thickness measuring instrument is a measurement light protection unit formed between a cover glass that transmits the measurement light, the first reflected light, and the second reflected light, and the plate-shaped work held by the cover glass and the holding table. The measurement light protection unit can switch between a case having an opening filled with fluid between the plate-shaped work held by the holding table and the cover glass, and water and air to supply the fluid to the case. In the case of a plate-shaped work having a portion and formed of one layer, the space between the upper surface of the plate-shaped work and the lower surface of the cover glass is filled with water to form an aqueous layer, and grinding is performed while measuring the thickness of the plate-shaped work. In the case of a plate-shaped work formed of two layers, the space between the upper surface of the plate-shaped work and the lower surface of the cover glass is filled with air to form an air layer, and grinding is performed while measuring the thickness of the upper layer .

According to this configuration, water or air is supplied to the case, and an aqueous layer or an air layer is formed between the cover glass and the plate-shaped work. The measurement light from the non-contact thickness measuring device passes through the cover glass and irradiates the plate-shaped work through the aqueous layer or the air layer. Since the optical path of the measurement light is protected by the water layer or the air layer, the measurement light is not blocked by the spray of the grinding water. At this time, since the fluid supplied to the case can be switched to water or air, the space between the cover glass and the plate-shaped work can be filled with a fluid suitable for the grinding process conditions. For example, when the refractive index of the upper surface of the plate-shaped work is close to water, air is supplied to the case, and when the refractive index of the plate-shaped work is sufficiently distant from water, water is supplied to the case. In addition, air is supplied to the case when the influence of spraying is small, and water is supplied to the case when the influence of spraying is large.

According to the present invention, the thickness of the plate-shaped work can be increased by switching the fluid between the cover glass and the plate-shaped work between water and air according to the grinding processing conditions such as the type of the work and the rotation speed at the time of grinding. It can be measured appropriately.

It is a perspective view of the grinding apparatus of this embodiment. It is explanatory drawing of the thickness measurement by the non-contact thickness measuring instrument of the comparative example. It is sectional drawing of the non-contact thickness measuring instrument of this embodiment. It is a schematic diagram of the fluid supply path of this embodiment. It is explanatory drawing of the thickness measurement by the non-contact thickness measuring instrument of this embodiment.

Hereinafter, the grinding apparatus of this embodiment will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of the grinding apparatus of the present embodiment. FIG. 2 is an explanatory diagram of thickness measurement by a non-contact thickness measuring device of a comparative example. Further, the grinding device is not limited to the device configuration dedicated to grinding as shown in FIG. 1, and for example, a fully automatic type machining in which a series of machining such as grinding, polishing, and cleaning is performed fully automatically. It may be incorporated into the device.

As shown in FIG. 1, the grinding apparatus 1 is configured to grind the plate-shaped work W held on the holding table 20 by using a grinding wheel 46 in which a large number of grinding wheels 47 are arranged in an annular shape. The plate-shaped work W is carried into the grinding device 1 with the protective tape T attached, and is held on the holding table 20 via the protective tape T. The plate-shaped work W may be a plate-shaped member to be ground, a semiconductor wafer such as silicon or gallium arsenide, an optical device wafer such as ceramic, glass, or sapphire, or before device pattern formation. It may be an asslice wafer.

A rectangular opening extending in the X-axis direction is formed on the upper surface of the base 10 of the grinding device 1, and this opening is covered with a moving plate 11 movable together with the holding table 20 and a bellows-shaped waterproof cover 12. ing. Below the waterproof cover 12, a ball screw type advancing / retreating means (not shown) for moving the holding table 20 in the X-axis direction is provided. The holding table 20 is connected to a rotating means (not shown), and is configured to be rotatable by driving the rotating means. Further, on the upper surface of the holding table 20, a holding surface 21 for sucking and holding the plate-shaped work W is formed by a porous porous material.

The column 15 on the base 10 is provided with a grinding feed means 30 for grinding and feeding the grinding means 40 in a direction (Z-axis direction) for approaching and separating from the holding table 20. The grinding feed means 30 has a pair of guide rails 31 arranged on the column 15 parallel to the Z-axis direction, and a motor-driven Z-axis table 32 slidably installed on the pair of guide rails 31. .. Nut portions (not shown) are formed on the back surface side of the Z-axis table 32, and a ball screw 33 is screwed into these nut portions. The ball screw 33 is rotationally driven by the drive motor 34 connected to one end of the ball screw 33, so that the grinding means 40 is moved along the guide rail 31 in the Z-axis direction.

The grinding means 40 is attached to the front surface of the Z-axis table 32 via the housing 41, and is configured to rotate the grinding wheel 46 around the central axis by the spindle unit 42. The spindle unit 42 is a so-called air spindle, and rotatably supports the spindle shaft 44 inside the casing 43 via high-pressure air. A mount 45 is connected to the tip of the spindle shaft 44, and a grinding wheel 46 in which a large number of grinding wheels 47 are arranged in an annular shape is mounted on the mount 45. The grinding wheel 47 is formed by solidifying diamond abrasive grains with a binder such as a metal bond or a resin bond.

The height position of the grinding means 40 is measured by the linear scale 51. The linear scale 51 measures the height position of the grinding means 40 by reading the scale of the scale portion 53 provided on the surface of the guide rail 31 with the reading portion 52 provided on the Z-axis table 32. On the upper surface of the base 10, a non-contact thickness measuring device 60 for measuring the thickness of the plate-shaped work W via an arm 56 is cantilevered and supported. The non-contact thickness measuring device 60 irradiates the plate-shaped work W with measurement light such as infrared laser light, and measures the thickness from the optical path difference of the reflected light on the upper surface and the interface of the plate-shaped work W. The detailed configuration of the non-contact thickness measuring device 60 will be described later.

Further, the grinding device 1 is provided with a control means 90 that controls each part of the device in an integrated manner. The control means 90 is composed of a processor, a memory, and the like that execute various processes. The memory is composed of one or a plurality of storage media such as ROM (Read Only Memory) and RAM (Random Access Memory) depending on the intended use. In this grinding device 1, the plate-shaped work W is thinned to a predetermined thickness by rotating the grinding wheel 47 arranged on the grinding wheel 46 while pressing it against the upper surface of the plate-shaped work W. At this time, the grinding means 40 is controlled by the control means 90 based on the measurement results of the linear scale 51 and the non-contact thickness measuring device 60.

By the way, as shown in FIG. 2A, in the non-contact thickness measuring device 95 of the comparative example, the non-contact thickness measuring device 95 and the plate-shaped work W are used so that the measurement light is not blocked by the spray of the grinding water scattered during the grinding process. The space is sealed with water. When the silicon wafer W1 is ground as a plate-shaped work W, the measurement light is transmitted through the water layer between the non-contact thickness measuring device 95 and the silicon wafer W1, so that the optical path of the measurement light is transmitted by spraying the grinding water. Is not blocked. Therefore, the silicon wafer W1 can be ground while accurately measuring the thickness of the silicon wafer W1 by the reflected light from the upper surface and the lower surface of the silicon wafer W1.

However, as shown in FIG. 2B, when the resin layer W2 is formed on the upper surface of the silicon wafer W1 as the plate-shaped work W, the space between the non-contact thickness measuring instrument 95 and the resin layer W2 is sealed with water. Then, the thickness of the resin layer W2 cannot be measured. This is because the refractive index of the resin (1.4 to 1.5) and the refractive index of water (1.33) are close to each other, so that the measured light is appropriately reflected at the interface between water and the resin (upper surface of the resin layer W2). This is because it does not. Although the optical path of the measurement light can be protected from the spray of grinding water in the water layer between the non-contact thickness measuring instrument 95 and the plate-shaped work W, the measurement light is not properly reflected on the upper surface of the resin layer W2, so that the resin is used. It is not possible to grind while measuring the thickness of layer W2.

Further, when grinding the silicon wafer W1 as the plate-shaped workpiece W (see FIG. 2A), the spray of grinding water tends to scatter at high speed rotation of the grinding wheel 46 (see FIG. 1), but the grinding water is easily scattered at low speed rotation of the grinding wheel 46. The spray is hard to scatter. Therefore, when the spray of the grinding water is difficult to scatter, the measurement accuracy by the non-contact thickness measuring device 95 is higher when the measurement is performed without sealing the space between the non-contact thickness measuring device 95 and the plate-shaped work W with water. .. Therefore, in the non-contact thickness measuring device 60 (see FIG. 3) of the present embodiment, the fluid between the non-contact thickness measuring device 60 and the plate-shaped work W can be switched between water and air, so that the plate-shaped work W can be switched. The thickness is measured according to the grinding conditions such as the type and the rotation speed of the grinding wheel 46.

Hereinafter, the non-contact thickness measuring device of the present embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 is a schematic cross-sectional view of the non-contact thickness measuring instrument of the present embodiment. FIG. 4 is a schematic diagram of the fluid supply path of the present embodiment.

As shown in FIG. 3, the non-contact thickness measuring instrument 60 measures toward the plate-shaped work W so as to permeate the fluid layer from the inside of the measuring instrument main body 61 while supplying the fluid to the upper surface of the plate-shaped work W. It is configured to irradiate light and measure the thickness of the plate-shaped work W. A light emitting unit 62, a half mirror 63, and a light receiving unit 64 are housed inside the measuring instrument main body 61, and an optical path of measurement light is formed by these members. A cover glass 65 that serves as an entrance / exit for measurement light and reflected light is provided on the lower surface of the measuring instrument main body 61, and the inside and outside of the measuring instrument main body 61 are liquid-tightly partitioned by the cover glass 65.

The measuring instrument main body 61 is provided with a measuring light protection unit 70 that protects the measuring light between the cover glass 65 and the plate-shaped work W. The measurement light protection unit 70 has a case 71 for storing the fluid in the lower part of the measuring instrument main body 61, and a switching unit 75 for switching the fluid supplied to the case 71 between water and air. A water supply source 76 and a supply port 72 connected to the air supply source 77 are formed on the side surface of the case 71, and a plate-shaped work such as water or air supplied to the case 71 is formed on the lower surface of the case 71. An opening 73 for discharging is formed on the upper surface of W. The case 71 fills the space between the plate-shaped work W and the cover glass 65 with a fluid to protect the optical path of the measurement light from the spray of grinding water.

In the non-contact thickness measuring instrument 60, the connection destination of the supply port 72 of the case 71 is switched between the water supply source 76 and the air supply source 77 by the switching unit 75. For example, when the plate-shaped work W is a silicon wafer W1 (see FIG. 5A), the connection destination of the supply port 72 is switched to the water supply source 76, and water is supplied between the cover glass 65 and the plate-shaped work W. To. When the resin layer W2 having a refractive index close to that of water is formed on the upper surface of the plate-shaped work W (see FIG. 5B), the connection destination of the supply port 72 is switched to the air supply source 77 to cover the cover glass 65. Air is supplied between the plate-shaped work W and the plate-shaped work W. In this way, the fluid is switched between water and air according to the material (refractive index) of the upper surface of the plate-shaped work W.

Here, since the refractive indexes of water and air are different, it is necessary to change the focal length of the non-contact thickness measuring instrument 60. Therefore, when switching between water and air, the set distance between the cover glass 65 and the plate-shaped work W is adjusted. For example, the refractive index of water is 1.33, the refractive index of air is about 1.00, and the setting when measuring the thickness with air is based on the set distance a (see FIG. 5A) when measuring the thickness with water. The distance b (see FIG. 5B) is expressed by the following equation (1).
Equation (1)
b = a / 1.33

By adjusting the set distance according to the refractive index in this way, the error in the measurement result due to the refractive index of water and air is corrected. When measuring the same measurement target, the same thickness is measured even if water and air are switched and measured by this correction. When an air layer is formed between the non-contact thickness measuring instrument 60 and the plate-shaped work W, the optical path of the measurement light is protected by the air layer, but the spraying of grinding water can be completely prevented. It may not be possible. When the spray enters the air layer, the thickness is measured to be thicker than the actual thickness. Therefore, the ratio of the spray in the air layer may be predicted to correct the measurement result.

In the non-contact thickness measuring device 60, the measurement light emitted from the light emitting unit 62 passes through the cover glass 65 and is irradiated to the plate-shaped work W through the fluid between the cover glass 65 and the plate-shaped work W. At this time, by selecting a fluid having a refractive index significantly different from that of the upper surface of the plate-shaped work W, the measurement light is reflected as the first reflected light on the upper surface of the plate-shaped work W, and the measurement light transmitted through the upper surface is plate-shaped. It is reflected as the second reflected light at the interface of the work W. The first and second reflected light passes through the cover glass 65 again and is reflected by the half mirror 63 toward the light receiving portion 64. Then, the light receiving unit 64 measures the thickness of the plate-shaped work W from the optical path difference between the first and second reflected lights.

Further, since the optical path of the measurement light is protected by the fluid between the cover glass 65 and the plate-shaped work W, it is possible to measure the thickness of the plate-shaped work W without being affected by the spray of grinding water. ing. The configuration is not limited to switching the fluid between water and air according to the type of the plate-shaped work W, and the fluid may be switched between water and air according to the rotation speed of the grinding wheel 46 (see FIG. 1).

As shown in FIG. 4, water is supplied from the water supply source 76 through the first flow path 81 to the supply port 72 of the case 71 of the non-contact thickness measuring instrument 60, and the air supply source is supplied through the second flow path 82. Air is supplied from 77. A water layer forming valve 84 and a first throttle valve 85 for the water layer are provided in the middle part of the first flow path 81, and an air layer forming valve 86 and an air layer forming valve 86 are provided in the middle part of the second flow path 82. A second throttle valve 87 for the air layer is provided. Further, a bypass flow path 83 is connected to the second flow path 82 so as to bypass the second throttle valve 87, and a third throttle valve 88 for drying and a drying air valve 89 are connected to the bypass flow path 83. Is provided.

A control means 90 is electrically connected to the water layer forming valve 84, the air layer forming valve 86, and the dry air valve 89, and the fluid supplied to the case 71 is switched between water and air by opening and closing the valve by the control means 90. Be done. As described above, the switching portion 75 is composed of the water layer forming valve 84, the air layer forming valve 86, and the drying air valve 89. When the water layer forming valve 84 is opened and the air layer forming valve 86 is closed, the water from the water supply source 76 is throttled to a predetermined amount (1-2 [l / min]) by the first throttle valve 85. Is supplied to the case 71. As a result, an aqueous layer is formed between the cover glass 65 and the plate-shaped work W, and the aqueous layer protects the optical path of the measurement light from spraying and the like during grinding.

When the air layer forming valve 86 is opened and the drying air valve 89 is closed while the water layer forming valve 84 is closed, the air from the air supply source 77 is discharged by the second throttle valve 87 to a predetermined amount of air (4). It is narrowed down to ~ 5 [l / min]) and supplied to the case 71. As a result, an air layer is formed between the cover glass 65 and the plate-shaped work W, and the air layer protects the optical path of the measurement light from sprays and the like during grinding. The first and second throttle valves 85 and 87 are different depending on the distance between the cover glass 65 and the plate-shaped work W, but the space between the cover glass 65 and the plate-shaped work W can be filled with water or air. It suffices if it can be adjusted to the flow rate of.

Further, when the air layer forming valve 86 and the dry air valve 89 are opened while the water layer forming valve 84 is closed, the air from the air supply source 77 bypasses the second throttle valve 87 and bypasses the bypass flow path 83. Flow into. This is because the opening area of the third throttle valve 88 of the bypass flow path 83 is wider than that of the second throttle valve 87 of the second flow path 82. Then, the air in the bypass flow path 83 is throttled to a predetermined amount of air (40 to 50 [l / min]) by the third throttle valve 88, and is supplied to the case 71 through the second flow path 82. As a result, when the air layer is formed after the water layer is formed between the cover glass 65 and the plate-shaped work W, a large amount of air flows into the case 71, water droplets in the case 71 are removed, and the plate is formed. The work W is dried.

The thickness measurement by the non-contact thickness measuring device will be described with reference to FIG. FIG. 5 is an explanatory diagram of thickness measurement by the non-contact thickness measuring device of the present embodiment. FIG. 5A shows an example of measuring the thickness of the silicon wafer, and FIG. 5B shows an example of measuring the thickness of the resin layer on the silicon wafer. The measurement target of the non-contact thickness measuring device is not limited to the silicon wafer and the resin layer, and can be changed as appropriate. Further, as described above, when measuring the plate-shaped work by switching between water and air, the set distance between the cover glass and the holding table is also adjusted.

As shown in FIG. 5A, the silicon wafer W1 as the plate-shaped work W is held on the holding table 20 via the protective tape T. Since the refractive index of water is significantly different from that of the silicon wafer W1, the case 71 is cut off from the air supply source 77 by the switching unit 75 and connected to the water supply source 76. As a result, water is supplied from the water supply source 76 into the case 71, and the water layer S1 is formed between the cover glass 65 and the silicon wafer W1. In this state, when the measurement light L0 is emitted from the light emitting unit 62, the measurement light L0 is transmitted through the half mirror 63 and the cover glass 65, and the measurement light L0 is irradiated to the silicon wafer W1 through the aqueous layer S1. To.

The measurement light L0 is reflected as the first reflected light L1 on the upper surface of the silicon wafer W1, and the measurement light L0 is reflected as the second reflected light L2 at the interface between the silicon wafer W1 and the protective tape T. The first and second reflected lights L1 and L2 pass through the water layer S1 again, pass through the cover glass 65, and are reflected by the half mirror 63 toward the light receiving portion 64. The light receiving unit 64 measures the thickness of the silicon wafer W1 from the optical path difference (interference difference) of the first and second reflected lights L1 and L2. As described above, in the thickness measurement of the silicon wafer W1, when the amount of sprayed grinding water is small as in the case of low-speed rotation of the grinding wheel 46 (see FIG. 1), between the cover glass 65 and the silicon wafer W1. The air layer S2 (see FIG. 5B) may be formed.

As shown in FIG. 5B, a silicon wafer W1 with a resin layer W2 as a plate-shaped work W is held on a holding table 20 via a protective tape T with the resin layer W2 facing upward. Since the refractive index of water is close to that of the resin layer W2, the switching unit 75 cuts off the case 71 from the water supply source 76 and connects it to the air supply source 77. As a result, air is supplied from the air supply source 77 into the case 71, and the air layer S2 is formed between the cover glass 65 and the resin layer W2. In this state, when the measurement light L0 is emitted from the light emitting unit 62, the measurement light L0 is transmitted through the half mirror 63 and the cover glass 65, and the measurement light is irradiated to the resin layer W2 through the air layer S2. ..

The measurement light L0 is reflected as the first reflected light L1 on the upper surface of the resin layer W2, and the measurement light L0 is reflected as the second reflected light L2 at the interface between the resin layer W2 and the silicon wafer W1. The first and second reflected lights L1 and L2 pass through the air layer S2 again through the cover glass 65, and are reflected by the half mirror 63 toward the light receiving portion 64. The light receiving unit 64 measures the thickness of the resin layer W2 from the optical path difference between the first and second reflected lights L1 and L2. By forming the air layer S2 instead of the water layer S1 in this way, the refractive indexes of the resin layer W2 and the air are sufficiently separated from each other, so that the interface between the air layer S2 and the resin layer W2 (the upper surface of the resin layer W2). ) Can appropriately reflect the measurement light.

As described above, according to the grinding apparatus 1 of the present embodiment, water or air is supplied to the case 71 of the non-contact thickness measuring instrument 60, and an aqueous layer or an aqueous layer or a plate-shaped work W is provided between the cover glass 65 and the plate-shaped work W. An air layer is formed. The measurement light from the non-contact thickness measuring device 60 passes through the cover glass 65 and is irradiated to the plate-shaped work W through the aqueous layer or the air layer. Since the optical path of the measurement light is protected by the water layer or the air layer, the measurement light is not blocked by the spray of the grinding water. At this time, since the fluid supplied to the case 71 can be switched to water or air, the space between the cover glass 65 and the plate-shaped work W can be filled with a fluid suitable for the grinding processing conditions. For example, when the refractive index of the upper surface of the plate-shaped work W is close to water, air is supplied to the case 71, and when the refractive index of the plate-shaped work W is sufficiently distant from water, water is supplied to the case 71. Will be done. Further, air is supplied to the case 71 when the influence of the spray is small, and water is supplied to the case 71 when the influence of the spray is large.

In the present embodiment, the fluid is switched between water and air according to the grinding conditions such as the type of the plate-shaped work W and the rotation speed of the grinding wheel 46, but the configuration is not limited to this. The fluid may be switched between water and air according to other conditions.

Further, in the present embodiment, when the upper surface of the plate-shaped work W is made of silicon, an aqueous layer is formed, and when the upper surface of the plate-shaped work W is made of resin, an air layer is formed. It is not limited to the configuration. The material of the upper surface of the plate-shaped work W is not particularly limited, and water and air may be switched according to the refractive index of the upper surface of the plate-shaped work W.

Further, in the present embodiment, the non-contact thickness measuring device 60 is configured to function as an air nozzle for drying the plate-shaped work W, but the non-contact thickness measuring device 60 does not have to have the function of the air nozzle.

Moreover, although the present embodiment and the modified example have been described, as another embodiment of the present invention, the above-described embodiment and the modified example may be combined in whole or in part.

Further, the embodiment of the present invention is not limited to the above-described embodiment, and may be variously modified, replaced, or modified without departing from the spirit of the technical idea of the present invention. Furthermore, if the technical idea of the present invention can be realized in another way by the advancement of technology or another technology derived from it, it may be carried out by using that method. Therefore, the scope of claims covers all embodiments that may be included within the scope of the technical idea of the present invention.

Further, in the present embodiment, the configuration in which the present invention is applied to the grinding apparatus has been described, but it is possible to apply the present invention to other apparatus capable of appropriately measuring the thickness of the plate-shaped work.

As described above, the present invention has an effect that the thickness of the plate-shaped workpiece can be appropriately measured according to the grinding processing conditions, and in particular, grinding used for grinding a silicon wafer with a resin layer. Useful for equipment.

1 Grinding device 20 Holding table 40 Grinding means 47 Grinding grindstone 60 Non-contact thickness measuring instrument 62 Light emitting part 64 Light receiving part 65 Cover glass 70 Measuring light protection part 71 Case 73 Opening 75 Switching part L0 Measuring light L1 First reflected light L2 First 2 reflected light S1 water layer S2 air layer W plate-shaped work W1 silicon wafer (plate-shaped work)
W2 resin layer (plate-shaped work)

Claims (1)

A holding table that holds a plate-shaped work consisting of one layer or two layers, an upper layer and a lower layer, a grinding means that grinds the plate-shaped work held by the holding table with a grinding wheel, and a plate-shaped work that is ground by the grinding means. The first reflected light that is irradiated with the measurement light and reflected on the upper surface of the plate-shaped work and the second reflected light that the measurement light that has passed through the upper surface is reflected at the lower surface of the one layer or the interface between the upper layer and the lower layer. a grinding apparatus and a non-contact thickness gauge for measuring the thickness or the upper layer of the thickness of the plate-shaped workpiece from the optical path difference between the light receiving to the first reflected light and the second reflected light,
The non-contact thickness measuring device is formed between a cover glass that transmits the measurement light, the first reflected light, and the second reflected light, and a plate-shaped work held by the cover glass and the holding table. Equipped with a measuring light protection unit, and
The measurement light protection unit is a case having an opening filled with a fluid between the plate-shaped work held by the holding table and the cover glass, and a switching unit capable of switching the fluid supplied to the case between water and air. With and
In the case of a plate-shaped work formed of the single layer, the space between the upper surface of the plate-shaped work and the lower surface of the cover glass is filled with water to form an aqueous layer, and the plate-shaped work is ground while measuring the thickness.
In the case of a plate-shaped work formed of the two layers, the space between the upper surface of the plate-shaped work and the lower surface of the cover glass is filled with air to form an air layer, and grinding is performed while measuring the thickness of the upper layer. apparatus.

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